An earlier version of this page borrowed clinical trials run on patients with serious diagnoses, and on children, to describe what an amino acid might do in a cup of coffee. It also carried a bar chart with numbers on it that nobody had measured.
All of it is gone. Here is what is left, which is enough.
What L-Theanine Is
L-theanine is an amino acid. Its full chemical name is gamma-glutamylethylamide, which tells you it is a relative of glutamic acid with an ethylamide group attached.
Your body does not make it. If it is in you, you ate or drank it. That is the whole of what "diet-derived" means, and it is unremarkable: the same is true of vitamin C.
Where It Comes From
L-theanine is unusual in nature. It occurs in only a handful of organisms, and it is concentrated in one.
| Source | What is true |
|---|---|
| Tea, Camellia sinensis | By far the principal dietary source. Green, black and white tea all come from this plant, and all contain it |
| A single mushroom | Xerocomus badius, the bay bolete. One of the very few non-Camellia organisms known to produce it |
| Mushrooms generally | No. This page used to say it occurs across culinary and functional species. It does not, and none of the five in our coffee produce it |
If Lion's Mane or Reishi contained meaningful L-theanine, no brand would need to buy any. The reason it is on the ingredient list is that the mushrooms do not supply it.
The Two Mirror Images
Here is the part that separates a serious ingredient from a cheap one, and it takes thirty seconds to understand.
Many molecules come in two forms that are mirror images of each other, like your left and right hands. Chemists call them isomers. They have identical formulas and behave completely differently in a living system, because biology is built from one hand and not the other.
Theanine has an L-isomer and a D-isomer. The L form is the one that occurs in tea. The D form does not.
Identical formula. Opposite handedness. Cheap synthetic theanine contains roughly half of each.
Cheap bulk theanine is often made by chemical synthesis, which produces both hands at once, roughly half and half. It is sold, honestly enough, as "theanine". It is not the same material as the one in a teacup.
Two products can both say 100mg of theanine on the label, and one of them can be half a molecule your body has never met.
L-Theanine vs Suntheanine®
Suntheanine® is a patented ingredient made by Taiyo. It is produced by enzymatic fermentation, a process that mimics what the tea plant does, rather than by chemical synthesis or by extracting it from leaves.
The result is over 99 percent the pure L-isomer. That is the difference, and it is the entire difference. It is also why it costs several times what bulk theanine costs, and why most mushroom coffees contain none at all.
Two routes to the same formula. Only one of them arrives at the molecule tea makes.
chemical synthesis≈ 50%
enzymatic fermentation> 99%
Two bars. The first is what a fifty-fifty synthetic mixture means, by definition. The second is the manufacturer's stated specification for Suntheanine®. Neither bar is an outcome, an effect, or a promise. They describe what is in the powder, not what it does in a person.
| Bulk theanine | Suntheanine® | |
|---|---|---|
| How it is made | Usually chemical synthesis | Enzymatic fermentation |
| What you get | A mixture of both isomers | Over 99 percent L-isomer |
| Matches what is in tea | Partly | Yes |
| Which the trials used | Generally not | The trials below used L-theanine |
| Cost | Low | The most expensive ingredient in our cup |
We use 100mg per serving, in both the 500mg and the 1000mg mushroom strengths. It does not scale with the mushrooms, because the reason for it has nothing to do with them.
What Has Actually Been Tested
Three double-blind, placebo-controlled trials. All three tested L-theanine together with caffeine, which is the pairing that matters for a coffee. Here is what each one measured, and what each one found.
Owen, Parnell, De Bruin & Rycroft, 2008
Measured speed and accuracy on an attention-switching task. The combination improved both at sixty minutes, and reduced susceptibility to distraction at sixty and ninety minutes, against placebo.
Giesbrecht, Rycroft, Rowson & De Bruin, 2010
Improved task-switching accuracy. Higher self-reported alertness, lower self-reported tiredness.
The same paper reported a small increase in systolic blood pressure with the combination. It is in the abstract. It has never been on this page before.
Haskell, Kennedy, Milne, Wesnes & Scholey, 2008
Tested L-theanine alone, caffeine alone, and the two together. The combination behaved differently from either on its own. The doses were considerably higher than ours, and we say so rather than borrow the result.
Owen 2008 and Giesbrecht 2010 were both funded by Unilever R&D, which sells tea-based drinks. Both are peer-reviewed, double-blind and placebo-controlled, which is more than most of this industry can say for its citations. We disclose the funding because it is relevant and because you would not otherwise know.
Why 100mg
Four bars. Three are published doses from the trials above. The fourth is what is in our cup. Nothing here is an outcome, an effect, or a promise. It is four numbers, and they are the only four we have.
We chose 100mg because Owen used 100mg and Giesbrecht used 97mg. That is the entire reasoning. A brand that puts 25mg in a serving and cites these papers is citing a study of something else.
What This Page Will Not Say
- Clinical trials run on patients, borrowed to describe a coffee
- A trial run on children with a diagnosis
- Anything at all about an organ or a condition a doctor treats
- A bar chart of numbers nobody measured
- Claims about what this drink does to your mood or your night
- The molecule. Gamma-glutamylethylamide, an amino acid
- The source. Tea, and one bolete. Not our mushrooms
- The isomer. Over 99 percent L, by fermentation
- The dose. 100mg, matching two published trials
- The funding behind those trials, and the blood-pressure finding
The old page promised that this amino acid would help you "turn up the volume on yourself". We do not know what that means, and neither did whoever wrote it.
The Part Nobody Mentions: Taste
L-theanine has a flavour. It is one of the compounds responsible for umami, the savoury fifth taste, and it is a large part of why a well-made green tea has a rounded, brothy sweetness rather than pure astringency.
In coffee it does something similar. It softens the edges. This is a claim about flavour, which is the one kind of claim a food is always allowed to make, and the one this industry seems least interested in.
Cautions
- Our coffee contains caffeine. Not for children. Pregnant women should follow their doctor's caffeine guidance.
- Giesbrecht 2010 reported a small rise in systolic blood pressure with the caffeine and L-theanine combination. If you manage your blood pressure, discuss it with your doctor.
- Anyone taking prescribed medication should ask before adding a supplement of any kind.
- Long-term data on daily L-theanine at this dose does not exist.
The Bottom Line
L-theanine is an amino acid from tea. Suntheanine® is a fermented, patented form of it that is over 99 percent the isomer nature uses. We put 100mg in every serving because that is the dose two published trials tested alongside caffeine.
Those trials measured attention-switching accuracy and self-reported alertness. They did not measure anything a doctor treats. One of them found a small rise in blood pressure, and both were funded by a company that sells tea.
That is the whole of what we know. Everything past it is somebody wanting to sell you a cup of coffee.
MycoSynergy Mushroom Coffee
Premium Indian Arabica, five mushroom fruiting-body extracts at 500mg or 1000mg per serving, and 100mg of Suntheanine® in both. Read the nine myths, including the ones we told.
See MycoSynergy →
